Adaptive modulation techniques for bandwidth and power efficient communication

Cognitive Radio (CR) describes a system which adapts to the environment in which it is operating and adjusts to its radio operating parameters dynamically and autonomously. It also learns from the actions undertook and its subsequent responses in the current environment. Progress in the field of radio technology enabled radios to manage their power, time and bandwidth resources in order to make best possible use of available spectrum. This project investigates how, when given a spectrum opportunity, one can transmit at lower possible power level that still maintains adequate secondary user Bit Error Rate (BER) performance. The bandwidth availability in cognitive radio dynamically change, and therefore adaptive modulation techniques may be used to most effectively utilise available bandwidth, while minimising interference to primary users. Moreover, techniques for monitoring the Signal-to-Noise ratio (SNR), Eb/No, and for adapting the modulation are also investigated. Analytical methods and digital communication systems simulations are devised. In addition, the performances of adaptive systems are presented. Furthermore, the performance results were obtained for adaptive systems transmitting over a Jakes model, Rayleigh Fading Channel. Both cases of very fast and slow fading Rayleigh channel and adapting to the changes in average SNR, Eb/No, therein are investigated.